In the field of manufacturing of optical lenses, there has been discussed techniques for obtaining highly heat-resistant optical lenses, by providing lens portions (optical parts) composed of a curable resin such as thermosetting resin, on a flat glass plate.
An exemplary method of manufacturing an optical lens ever developed is such as forming a diaphragm for adjusting quantity of incident light, which diaphragm is composed of a metal film formed on a substrate, and providing on the surface of the diaphragm a plurality of optical components composed of a curable resin, to thereby form a so-called “wafer lens”. A plurality of wafer lenses, respectively formed monolithically, are then stacked and bonded, while placing spacers in between or while bringing projections formed concurrently with the optical surface into contact, to thereby form a plurality of compound lenses, and the substrate is then diced so as to singulate the lens portions. This method of manufacturing successfully reduces manufacturing costs of optical lenses.
On the other hand, the dicing of the wafer lens for singulating the lens portions raises a technical problem specific to the wafer lens. Due to large internal stress of the lens portions, the lens portions may occasionally separate from the substrate. Especially for the case where the diaphragms are formed integrally with the substrate, an additional problem arises in that the separation may be induced by dicing, also between the lens portions and the substrate having the diaphragms formed thereon, between the substrate and the diaphragms, and at other various interfaces. In short, a subject of achieving adhesive force among the substrate, the diaphragms, and the individual layers composing the lens portions durable to the dicing still remains to be solved, in view of obtaining desirable optical systems.
As one of techniques of improving the adhesive force among the layers formed in the optical components, Patent Document 1 discloses a technique of providing a layer which contains silane coupling agent, between an anti-reflection film for suppressing reflection on the surface of the optical components, and a substrate which serves as a base, to thereby enhance adhesiveness of the anti-reflection film to the base.
Another known technique relates to a method of manufacturing a micro-lens array, in which an adhesiveness enhancing layer is provided between a die base and a photo-sensitive material (see Patent Document 2, for example).